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17 sie 2009 · In a SQL statement, using IsNull() makes no sense -- you'd instead use Is Null in the criteria, instead of testing for IsNull()=True. For zero-length strings, you test ="" rather than using a bunch of nested functions to get rid of the ZLS.
9 mar 2018 · Usually this is done via a comparison operator (=, >, <, etc.), but can be done with functions that resolve to one of those two values. Your's is simply a statement--one that doesn't make sense to the computer because it doesn't resolve to True or False. I would use the IsNull function (https://www.techonthenet.com/access/functions/advanced/isnull.
IsNull returns True if expression is Null; otherwise, IsNull returns False. If expression consists of more than one variable, Null in any constituent variable causes True to be returned for the entire expression. The Null value indicates that the Variant contains no valid data.
21 sty 2022 · Use the IsNull function to determine whether an expression contains a Null value. Expressions that you might expect to evaluate to True under some circumstances, such as If Var = Null and If Var <> Null , are always False .
This MSAccess tutorial explains how to use the Access IsNull function with syntax and examples. The Microsoft Access IsNull function returns TRUE if the expression is a null value. Otherwise, it returns FALSE.
23 lis 2015 · You must use IsNull(value) or Not Isnull(value) if you want to know if something is null. As an alternative method or to cover more bases you can use nz(VariableName) which returns a zero length string "" (which is also the same as vbNullString ) if VariableName is null.
15 sie 2023 · To explicitly check for Null in VBA, use the IsNull () function: Sub TestForNull (MyVar As Variant) If IsNull (MyVar) Then MsgBox "Passed variable is Null" End Sub. Be aware that T-SQL (the SQL Server flavor of SQL) has its own ISNULL () function which operates more like Access's Nz () function (described below).
